Many central laboratories receive specimens from remote collection stations, satellite laboratories, physician office laboratories (POLs), home health care nurses, and the like. Laboratory environments have changed such that more and more specimens are collected remotely and transported to core labs for analysis. In these situations, the specimens may not reach the testing laboratory until several hours or days after collection. Furthermore, the conditions of transport may vary widely. Additionally, stored specimens are often retrieved for add-on or repeat testing. In each of these situations, time and temperature can influence analyte stability, and hence the actual observed value of a specimen tested after transportation and/or storage.
Previous studies have been conducted to evaluate the stability of analytes. However, in those studies, either time or temperature was fixed. In the real world, the laboratory may have little control over the transport and storage conditions of specimens from remote locations.
Analyte values are used by physicians and medical professionals to make diagnoses of diseases and other health related problems. Furthermore, analyte values are used in medical treatments, for therapeutic monitoring, to measure response to a treatment or therapy, and to follow the progression of a disease. The effectiveness of these uses are dependent on accurate determinations of analyte values. Because analyte values can change over time, any determination made based on observed analyte values at a later time can be affected by the degree of analyte degradation since the sample was taken. Therefore, it would be desirable to have an accurate model for estimating the initial values of analytes in a blood sample, given knowledge of the transport and storage conditions. Such conditions include the type of container used to store the sample, the temperature at which the sample was stored, and the time elapsed from when the sample was obtained to when it is actually tested.
Furthermore, it would be desirable to have testing equipment which incorporated such a model, to provide not only the actual observed value for a particular analyte, but also an accurate estimate of what the value was when the sample was taken, given knowledge of the transport and storage conditions, as discussed above.